;+
; NAME:
;       UNMATCH
; PURPOSE:
;       Remove the given indices from all indices of a vector with the
;       given length
; CALLING SEQUENCE:
;       result = UNMATCH(idx, N_ELEMENTS(arr))
; EXAMPLES:
;       a = dindgen(10)
;       b = WHERE(a MOD 3 EQ 1)
;       c = UNMATCH(b, N_ELEMENTS(a))
;           c now contains all indices where a MOD 3 NE 1
; KEYWORDS:
;       idx =
;       N_ELEMENTS(arr) = size of the array in one dimensional space
; REMARKS:
;       The example shows a case where one can easily get the other
;       values by means of rewriting the WHERE statement. This routine
;       is much more useful for when this is not possible, such as
;       wanting to have the opposite behaviour of MATCH, i.e. wanting
;       to have the indices of the values that do *NOT* match another
;       array.
;       For higher dimension removal, use UNMATCH in combination with
;       ARRAY_INDICES and INDICES_ARRAY. First convert the
;       multi-dimensional coordinates to one-dimensional coordinates,
;       remove them with UNMATCH and convert back to multi-dimensional
;       coordinates.
; DEPENDENCIES:
;       astro library REMOVE
; MODIFICATION HISTORY:
;       15/01/07 written by Eduard Westra
;-
FUNCTION unmatch, idx, no
  IF N_ELEMENTS(no) NE 1 THEN BEGIN
     MESSAGE, /CONTINUE, 'Not a value, but array. Just taking the N_ELEMENTS of it...'
     lno = N_ELEMENTS(no)
  ENDIF ELSE BEGIN
     lno = no
  ENDELSE
  idxRemoved = INDGEN(lno, TYPE=SIZE(lno, /TYPE))
  REMOVE, idx, idxRemoved
  RETURN, idxRemoved
END